The Balanomorph Barnacles of the Kermadec Islands.

By J. T. Linzey.

[Read before the Canterbury Branch, June 4, 1941; received by the Editor, October 30, 1941; issued separately, March, 1942.]

In 1908 Dr. W. R. B. Oliver made a collection of material from Sunday Island and forwarded the crustacea to Dr. C. Chilton for identification. The Crustacea of the Kermadecs, subsequently published in 1911, mentions four species of Lepas, but the sessile barnacle material was not described.

Balanus tintinnabulum subsp. tintinnabulum (Linnaeus).

Material: Three adult and five young specimens.

Locality: Denham Bay Beach.

These specimens seem to be most closely related to subsp. tintinnabulum of all the known forms. Further work on more material may show it to be a new subspecies. The chief differences are as follows: In the scutum the articular ridge is longer than in the above subspecies and the pit for the insertion of the depressor muscle is extremely deep. The tergum is broadly triangular with the carinal margin strongly convex. The spur, which is shorter than the above, is situated only from one to one and a-half times its own width from the basi-scutal angle. The parieties are fairly thick. Colour, purple.

Balanus tintinnabulum subsp. tintinnabulum occurs in tropical waters and is reported from such places as Hong Kong and Java by Pilsbry (1916, p. 57). He also reports that ships travelling from New Zealand to America have acquired this variety. However, as it has never been observed in this country, they must be considered to have been picked up in more northerly waters. Although there is a doubt that the specimens are to be referred to this subspecies, the presence of any subspecies of tintinnabulum is foreign to New Zealand waters.

Balanus decorus Darwin.

Material: Three large specimens.

Locality: Denham Bay Beach.

The specimens agree exactly with the New Zealand material. Balanus decorus is a typical member of the New Zealand Region, being found in Australia and New Zealand not only in the present times, but as a prominent species in Tertiary deposits (Withers, 1924, p. 25). Sunday Island is the most northerly point from which it has been reported.

Tetraclita purpurascens (Wood).

Material: A large number of specimens on basalt.

Locality: Sunday Island.

Tetraclita purpurascens is another species peculiar to the New Zealand region It is said to be quite common in Australia (Darwin, 1854, p. 337), and occurs in this country, while Broch reports it from as far south as Auckland Island (1922, p. 337).

Locality: Benham Bay and Fleetwood Bluff, on rocks between the tidemarks.

This species is not recorded from New Zealand, but occurs in New South Wales and South Africa (Darwin, 1854, p. 335). Gruvel says that it occurs in warm seas.

Elminius simplex Darwin.

Material: Two specimens from a fragment of Mytilus.

Locality: Sunday Island.

This species occurs in Australia, while its close ally, E. plicatus, is one of the most common of the New Zealand littoral species (Darwin, 1854, p. 353).

Creusia spinulosa Leach var. “8” Darwin.

Material: Several specimens sunk in a coral.

Locality: Cast up on “Low Flat Beach,” Sunday Island.

The material corresponds fairly closely with Darwin's description of variety 8 (1854, p. 375), more especially when it is remembered that he based this on only one specimen. A short description of the Sunday Island material is given here: Shell conical, but not steep. Walls strongly ribbed internally, with corresponding distinct ridges on the outer surface; outer lamina thin and single, thus parieties are without pseudopores. Radii well developed with edges formed of crenulate septa. Sheath pale purple. Basis thin, deeply cupformed and without pores; the whole cup being strongly crenulated, the crests fitting at their distal ends between the ribs of the walls and bearing along their length a regular row of small hemispherical papillae (the row is sometimes double). The opercular plates agree with Darwin's description except that the tooth on the basal margin of the scutum is smaller than indicated, more closely resembling his variety 2.

Creusia spinulosa is a typically tropical form, completely alien to New Zealand waters.

Chamaesipho columna (Spengler).

Material: One small specimen attached to Elminius simplex.

Locality: Denham Bay Beach.

The specimen is quite characteristic of the species which has been reported from nowhere outside the New Zealand region. Of this Broch says “and the peculiar genus Chamaesipho in no other place flourishes to an equal degree although only in a single species” (1922, p. 314).

Distribution: It has been known for a long time that the cirripede species tend to arrange themselves in large regional groups. Darwin shows New Zealand and Australian waters to be one of these regions. Further work has extended the southern limit down as far as the Subantarctic Islands. How far it is justifiable to include northern and western Australia in this division is a problem that future workers must solve. Thus in the meantime it is more convenient to consider a “New Zealand region” extending its western boundary along the south and east of Australia.

The cirripede fauna of the Kermadec Islands is thus of great interest, being the north-most point of this region from which a collection has been made. Unfortunately this list must be considered far from complete; for, as no dredging was undertaken, all the deeper water forms remain unknown.

Of the thirteen forms of cirripedes now described from the Kermadecs, B. decorus, T. purpurascens, E. simplex, C. columna, and L. anatifera var. C are peculiar to the New Zealand Region. C. spinulosa, L. anatifera var. A and var. B are distinctly foreign to the region. The other species are more or less cosmopolitan and bear no particular significance. The fauna as a whole would indicate that the Kermadec Islands are situated in the New Zealand Region.

The writer wishes to thank Dr. W. R. B. Oliver for the use of the material which has since been placed in the Canterbury Museum.